now i'm a little rusty on linear algebra, so correct me if i'm wrong. you said topsqaurk was right, so we are given that:
L(2, -3, -5) = (0, 4, 8)
L(0, 4, 8) = (2, 9, 2)
however, the standard matrix for L will be a 3x3 matrix, and therefore, we need at least 3 examples of transformations to find it.
unless there was some other way which i am not remembering at the moment